1. Field of the Invention
The present invention relates to a height output device, a height output method, and a program.
2. Description of the Related Art
Such navigation device, in related art, that calculates a position of the device based on global positioning system (GPS) signals, which are transmitted from GPS satellites, so as to display the calculated position on a map screen has been widely used. A navigation device is fixedly installed on an automobile or a ship and used in automobile driving or ship handling, for example. Further, a small-sized portable navigation device (PND) is used by a user who moves by bicycle or on foot.
By the way, not only a position of the navigation device but also a height of the navigation device can be calculated based on GPS signals. Positioning in which a height as well as a position of the navigation device are calculated is called three-dimensional (3D) positioning. The 3D positioning is enabled when the navigation device can receive GPS signals from four or more GPS satellites in a case considering error calibration. On the other hand, when the navigation device can receive GPS signals from only three GPS satellites, only a position can be calculated by two-dimensional (2D) positioning.
A height display function is used for informing a present height to a user on a screen of a common car navigation device. In addition, the height display function is very important also for a PND which is taken along by users including travelers and mountain climbers, for example. Therefore, Japanese Unexamined Patent Application Publication No. 2006-214993 proposes a navigation device capable of outputting a height which is determined based on a measurement result of atmospheric pressure when the 3D positioning based on GPS signals is difficult.